摘要
为解决小电流接地系统高阻接地故障检测的难题,分析了单相接地故障前后相电流变化特征:故障线路的故障相与非故障相电流变化量之差等于接地故障电流,非故障线路的故障相与非故障相电流变化量相等;并由故障相电压与故障电流之比计算出接地故障电阻,发明了基于接地故障电阻测量的高阻接地保护方法。EMTP仿真分析和动模实验测试结果表明,该保护方法能够保护各种高阻接地故障,具有较高的保护精度和可靠性,适合在配电自动化终端单元(FTU)上就地实现。
Neutral Ineffectively Earthed Power Systems （NIEPS） include neutral unearthed system, neutral earthed with high resistance system and neutral resonance earthed system. Single-phase grounding faults potentially cause cane bombing or phase-to-phase faults in NIEPS, and the safety and power quality of the distribution system will be affected. High impedance grounding faults are difficult to detect with traditional methods in NIEPS because of minor fault current, fault arc, harmonies influence and the protection principle limitation. In order to improve the precision and reliability of traditional grounding fault protection schemes for NIEPS, the characteristics of phase current variations before and after grounding fault occurring are analyzed in the paper. The difference of phase current variations between the fault phase and a normal phase in the faulted feeder equals to the grounding fault residual current, and the difference in the normal feeder equals to zero. The fault resistance equals the ratio between fault phase voltage and fault current. The fault resistance based protection is then put forward. When the fault current is higher than its threshold or the resistance is lower than its threshold, grounding fault occurs in the protected feeder. EMTP simulation and experimental results show that the measurement is with high precision, and the protection is with high sensitivity and robustness to detect high impedance grounding faults. They can satisfy the requirements of distribution automation systems and be implemented on Field Terminal Units （FTU）, which is installed in distribution automation system and can only measure the current of the protected feeder.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2007年第1期26-30,共5页
High Voltage Engineering
基金
国家自然科学基金(50207001
50577001)
教育部新世纪优秀人才计划(NECT-04-0781)
霍英东教育基金会青年教师基金(101058)资助项目
关键词
小电流接地系统
高阻接地故障
故障选线
继电保护
相电流
neutral ineffectively earthed power systems
high impedance grounding faults
fault detection
protective relay
phase current
